The invention relates to the technical sector of automatic machines for packing articles in tubular containers.
The tubular containers, or tubes, are to be directed one by one and in a predetermined orientation in a conveyor line which can be straight or a carousel, destined to transfer the tubes to a filling station in which special dispenser organs fill them with the articles.
Downstream of the filling station, further stations are provided for control, closure of the tubes and for any rejecting of unsatisfactory articles.
The technical problem posed, which relates to the present invention, consists in correctly orientating the tubes as they are entering the conveyor line, such that the open heads thereof are correctly facing the side of the dispensing organs, and therefore usually facing upwards.
The tubes which are normally used, apart from their size, are of two types: one which exhibits a broadened edge at the open head thereof, a sort of neck, or collar, and one which is without this broadening.
The first operation consists in arranged the tubes with a same orientation, for example in lines according to the longitudinal axes thereof or placed side-by-side, starting from a store in which the tubes are loosely accumulated.
Thereafter for each tube it is necessary to find where the open head is located, and on the basis of this the handling organs therefor can be piloted to pick it up and place it in the conveyor line.
For this second operation, known realisations use television camera systems which can detect the position of the open head, and handlers constituted by robots operating on at least three axes.
It is clear that these devices are not only expensive but require, in order to function in synchrony, a complex management program which is however liable to error since it is entirely based on visual data received from the cameras, and therefore on the chromatic contrast between contiguous zones of the image produced, which can sometimes be insufficient for obtaining data which truly relate to actuality.
Only for tubes having a collar can a known device be used, which is able to orientate all the tubes with the openings thereof facing upwards.
The device comprises a horizontal conveyor line, constituted by two belts arranged side-by-side, onto which the tubes are supplied in a line according to their longitudinal axes and having a random arrangement of the relative open and closed heads.
In an initial tract of the conveyor line, the belts are side-by-side with a free space which is smaller than the minimum diameter of the tube, so that the tube is supported at both the open head and the closed head; downstream of the initial tract the belts are slightly distanced from one another such that the free space between them is greater than the minimum diameter of the tube but smaller than the maximum diameter thereof, i.e. the collar area.
When the closed head of the tube, i.e. the head with the smaller diameter, reaches the point where the belts are reciprocally furthest away from each other, the tube is no longer retained and the fall thereof causes a spontaneous rotation of the tube which is then vertical with the opening thereof facing upwards, retained by the belts at the collar zone thereof.
The spontaneous rotation described above occurs independently of the fact that the closed head is arranged upstream or downstream according to the advancement direction of the tube itself.
In order to function, the known device described above requires tubes having a quite-pronounced collar zone, such that the difference between the minimum and maximum diameters thereof is sufficient for the belts to retain the collar while the gap is also sufficient to enable the spontaneous rotation of the tube.